I have two Yamaha receivers, which are visible, but grayed out in the list Device Picker.
There is a note next them: "Can't play this right now".
I have a big bunch of other devices that work and to which Spotify can be connected to via WIFI or LAN.
My devices, which are working (all are in the same network, most via WIFI, some computers are connected via LAN cable to the router): - Several Windows 10 Computers. I tested both old and latest version of Spotify desktop. - One HP Z230 PC, W10 1909 build 18363.535, Spotify Windows Store version (220.127.116.114.g282a2807). This one I had to fully clear (including registry) as it had both Desktop and Windows Store versions of Spotify installed. - Mac Mini and iMac 27 with old and latest Spotify. - iPhone 6 plus, iOS 12.4.3, Spotify v. 18.104.22.1684. - Huawei P20 Pro, Android 9, Spotify v. 22.214.171.1247. - iPad Air 2, iOS 13.2.3, Spotify v. 126.96.36.1994. - Two Amazon Echo Dot (3rd gen). - Sonos One (2nd gen). - Sonos Play 5 (1st gen).
My setup that has recently stopped working via Spotify Connect. They used to work just fine. They are both in same WIFI. Both have the newest firmware, just checked today. There has not been any firmware updates to either of these lately. These both do play Spotify via Airplay from iPhone but it is not a viable option. I did purchase these specific receivers because they support Spotify Connect! - Yamaha RX-V3070 - Yamaha WXA-50
I have contacted local Yamaha help center and done all troubleshooting what they asked (e.g. clear network cache by removing power from receiver and keeping it disconnected for a while, disabled music sharing and reconnected). Did not help.